linux-kernel - [RFC PATCH v2 1/3] powerpc/mm: prepare kernel for KAsan on PPC32

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Message-Id: <55ad0e6a00ba8abc008664fa8e367c1e2ce1f4cd.1545287470.git.christophe.leroy@c-s.fr>
Date:   Thu, 20 Dec 2018 06:40:36 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, npiggin@...il.com,
        aneesh.kumar@...ux.ibm.com
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [RFC PATCH v2 1/3] powerpc/mm: prepare kernel for KAsan on PPC32

In kernel/cputable.c, explicitly use memcpy() in order
to allow GCC to replace it with __memcpy() when KASAN is
selected.

Since commit 400c47d81ca38 ("powerpc32: memset: only use dcbz once cache is
enabled"), memset() can be used before activation of the cache,
so no need to use memset_io() for zeroing the BSS.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/kernel/cputable.c | 4 ++--
 arch/powerpc/kernel/setup_32.c | 6 ++----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index 2da01340c84c..9ea031b05f19 100644
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c
@@ -2145,7 +2145,7 @@ void __init set_cur_cpu_spec(struct cpu_spec *s)
 	struct cpu_spec *t = &the_cpu_spec;
 
 	t = PTRRELOC(t);
-	*t = *s;
+	memcpy(t, s, sizeof(*t));
 
 	*PTRRELOC(&cur_cpu_spec) = &the_cpu_spec;
 }
@@ -2160,7 +2160,7 @@ static struct cpu_spec * __init setup_cpu_spec(unsigned long offset,
 	old = *t;
 
 	/* Copy everything, then do fixups */
-	*t = *s;
+	memcpy(t, s, sizeof(*t));
 
 	/*
 	 * If we are overriding a previous value derived from the real
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 972c98d1e208..00b8f54fed29 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -74,10 +74,8 @@ notrace unsigned long __init early_init(unsigned long dt_ptr)
 {
 	unsigned long offset = reloc_offset();
 
-	/* First zero the BSS -- use memset_io, some platforms don't have
-	 * caches on yet */
-	memset_io((void __iomem *)PTRRELOC(&__bss_start), 0,
-			__bss_stop - __bss_start);
+	/* First zero the BSS */
+	memset(PTRRELOC(&__bss_start), 0, __bss_stop - __bss_start);
 
 	/*
 	 * Identify the CPU type and fix up code sections
-- 
2.13.3